U.S. patent application number 16/821302 was filed with the patent office on 2020-09-10 for laser processing head and laser processing system using same.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to Shinya DOMOTO, Kiyotaka EIZUMI, Kenji HOSHINO, Ryo ISHIKAWA, Naoya KATO, Doukei NAGAYASU, Hideaki YAMAGUCHI, Takayuki YAMASHITA.
Application Number | 20200282495 16/821302 |
Document ID | / |
Family ID | 1000004866539 |
Filed Date | 2020-09-10 |
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United States Patent
Application |
20200282495 |
Kind Code |
A1 |
KATO; Naoya ; et
al. |
September 10, 2020 |
LASER PROCESSING HEAD AND LASER PROCESSING SYSTEM USING SAME
Abstract
Laser processing head (20) of the present disclosure includes
housing (30), transparent protector (40), and temperature sensor
(70). Housing (30) includes an optical path of processing laser
light (LB). Transparent protector (40) is detachably fixed to
housing (30), passes processing laser light (LB), and suppresses
dust of work material (W) entering into housing (30). Here, the
dust is generated from the work material (W) irradiated with
processing laser light (LB). Temperature sensor (70) detects the
temperature of transparent protector (40).
Inventors: |
KATO; Naoya; (Osaka, JP)
; YAMASHITA; Takayuki; (Osaka, JP) ; NAGAYASU;
Doukei; (Hyogo, JP) ; HOSHINO; Kenji; (Hyogo,
JP) ; YAMAGUCHI; Hideaki; (Osaka, JP) ;
ISHIKAWA; Ryo; (Osaka, JP) ; DOMOTO; Shinya;
(Osaka, JP) ; EIZUMI; Kiyotaka; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
1000004866539 |
Appl. No.: |
16/821302 |
Filed: |
March 17, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2018/034717 |
Sep 20, 2018 |
|
|
|
16821302 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 26/10 20130101;
B23K 26/066 20151001; B23K 26/128 20130101; B23K 26/706 20151001;
B23K 26/0648 20130101; B23K 26/0626 20130101 |
International
Class: |
B23K 26/06 20060101
B23K026/06; B23K 26/10 20060101 B23K026/10; B23K 26/12 20060101
B23K026/12; B23K 26/066 20060101 B23K026/066; B23K 26/70 20060101
B23K026/70 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2017 |
JP |
2017-181747 |
Claims
1. A laser processing head comprising: a housing including an
optical path of a processing laser light; a transparent protector
configured to be detachably fixed to the housing, to pass the
processing laser light, and to suppress dust entering into the
housing, the dust being generated from the work material irradiated
with the processing laser light; and a temperature sensor
configured to detect a temperature of the transparent
protector.
2. The laser processing head according to claim 1, wherein the
processing laser light includes a near-infrared light, the
transparent protector has a glass plate having a portion configured
to pass the processing laser light, and the temperature sensor
includes an infrared radiation thermometer, the infrared radiation
thermometer being configured to optically detect a temperature of
the glass plate by detecting a peak wavelength of a far-infrared
light generated by a black-body radiation from the dust adhering to
the glass plate.
3. The laser processing head according to claim 2, wherein the
glass plate includes: an exposure region configured to pass the
processing laser light; and a non-exposure region configured not to
pass the processing laser light, and the temperature sensor
optically detects a temperature of the glass plate in the
non-exposure region.
4. The laser processing head according to claim 3, wherein the
housing includes a shade configured to block a light coming into
the temperature sensor from the glass plate in the exposure
region.
5. The laser processing head according to claim 1, wherein the
transparent protector includes: a glass plate including a portion
configured to pass the processing laser light; and a frame
configured to hold the glass plate, and the temperature sensor
detects a temperature of the glass plate by electrically detecting
a temperature of the frame.
6. A laser processing system comprising: a processing laser light
source; a housing including an optical path of a processing laser
light coming from the processing laser light source; a transparent
protector configured to be detachably fixed to the housing, to pass
the processing laser light, and to suppress dust entering into the
housing, the dust being generated from the work material irradiated
with the processing laser light; a temperature sensor configured to
detect a temperature of the transparent protector; and a controller
coupled to the processing laser light source and the temperature
sensor.
7. The laser processing system according to claim 6, wherein the
processing laser light includes a near-infrared light, the
transparent protector has a glass plate having a portion configured
to pass the processing laser light, and the temperature sensor
includes an infrared radiation thermometer, the infrared radiation
thermometer being configured to optically detect a temperature of
the glass plate by detecting a peak wavelength of a far-infrared
light generated by a black-body radiation from the dust adhering to
the glass plate.
8. The laser processing system according to claim 7, wherein the
glass plate includes: an exposure region configured to pass the
processing laser light; and a non-exposure region configured not to
pass the processing laser light, and the temperature sensor
optically detects the temperature of the glass plate in the
non-exposure region.
9. The laser processing system according to claim 8, wherein the
housing includes a shade configured to block a light coming into
the temperature sensor from the glass plate in the exposure
region.
10. The laser processing system according to claim 6, wherein the
transparent protector includes: a glass plate including a portion
configured to pass the processing laser light; and a frame
configured to hold the glass plate, and the temperature sensor
detects a temperature of the glass plate by electrically detecting
a temperature of the frame.
11. The laser processing system according to claim 6, the laser
processing system further comprising a display coupled to the
controller, wherein the controller causes the display to perform
one of displaying the temperature of the transparent protector
detected by the temperature sensor; and displaying an output
reduction rate representing an output reduction of the processing
laser light radiated to the work material, the output reduction
being caused by the dust adhering to the transparent protector.
12. The laser processing system according to claim 6, the laser
processing system further comprising an input unit coupled to the
controller, wherein the controller receives, via the input unit, a
set value of an output reduction rate representing an output
reduction of the processing laser light radiated to the work
material, the output reduction being caused by the dust adhering to
the transparent protector.
Description
[0001] This application is a U.S. national stage application of the
PCT International Application No. PCT/JP2018/034717 filed on Sep.
20, 2018, which claims the benefit of foreign priority of Japanese
patent application No. 2017-181747 filed on Sep. 21, 2017, the
contents all of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a laser processing head
and a laser processing system using this, and more particularly to
a laser processing head configured to detect the dirt of protective
glass--which is produced by the dust (sputters or fumes) generated
when laser light of a high power is radiated to a work material
(work)--, and to a laser processing system using this.
BACKGROUND ART
[0003] A laser processing head used for a laser processing system
includes a collecting lens that collects laser light of a high
power oscillated from a laser oscillation device. The collecting
lens further increases the energy density of the laser light, and
radiates the laser light to a work material to process the work
material (welding, fusing, or punching). At this time, the sputters
or fumes (for example, evaporated zinc metal particles) generated
from the work material can scatter into a surrounding embodiment,
and can contaminate the surface of the collecting lens. When the
sputters or fumes adhere to the collecting lens to contaminate the
lens, the optical characteristic (light transmittance or the like)
of the collecting lens reduces, and the intensity of the laser
light to be radiated to the work material decreases. Therefore, the
laser processing head includes a protective glass for protecting
the collecting lens from contaminants such as the sputters or
fumes.
[0004] For example, Patent Literature 1 describes a laser
processing head that includes a protective glass for protecting the
collecting lens from contaminants (dust) such as sputters or fumes.
The laser processing head further includes a dirt detecting means
for detecting the dirt adhering to the protective glass.
Furthermore, in the description, the laser processing head of
Patent Literature 1 suppresses the adhesion of the contaminants to
the protective glass of an air downstream side (rim), by blowing
off the contaminants with the air ejected from an air ejecting
means.
[0005] Patent Literature 1 describes a dirt detecting means
(optical fiber connected to an optical sensor) disposed at the rim
of the protective glass. The protective glass with contaminants
diffusely reflects the detection light which has been radiated
diagonally upward from a plurality of point light sources toward
the protective glass. The dirt detecting means detects the
diffusely reflected detection light. Patent Literature 1 describes
that, when the detection value of the diffusely reflected detection
light becomes higher than a previously set reference value, the
protective glass is replaced.
CITATION LIST
Patent Literature
[0006] PTL 1: Unexamined Japanese Patent Publication No.
2013-052440
SUMMARY OF THE INVENTION
[0007] Technical Problem(s)
[0008] However, a dirt detecting means described in Patent
Literature 1 is disposed on the rim (substantially the same height
level as the protective glass) of the protective glass. Therefore,
the intensity of the diffusely reflected light coming from
contaminants adhering to the protective glass is low and its
detection value also low, and hence the contaminants adhering to
the protective glass cannot be accurately detected. Due to the
described arrangement of the dirt detecting means, the following
phenomena occur: the dirt detecting means easily and directly
detects illumination light from a plurality of point light sources
or reflected light; and the dirt detecting means is apt to be
adversely affected by the light (disturbance light) scattered by
the contaminants such as sputters or fumes floating under the
protective glass.
[0009] The present disclosure is provided for solving the
above-mentioned problems. The present disclosure provides a laser
processing head for detecting the degree of the adhesion of the
contaminants in a method different from the conventional method,
and provides a laser processing system using this head.
Solution(s) to Problem(s)
[0010] A first aspect in accordance with the present disclosure
relates to a laser processing head. The laser processing head
includes a housing, a transparent protector that is detachably
fixed to the housing, and a temperature sensor that detects the
temperature of the transparent protector. The housing includes an
optical path of processing laser light. The transparent protector
passes the processing laser light, and suppresses dust, which is
generated from the work material irradiated with the processing
laser light, entering into the housing.
[0011] A second aspect in accordance with the present disclosure
relates to a laser processing system. The laser processing system
includes a processing laser light source, a housing, a transparent
protector that is detachably fixed to the housing, a temperature
sensor that detects the temperature of the transparent protector,
and a controller connected to the processing laser light source and
the temperature sensor. The housing includes an optical path of
processing laser light coming from the processing laser light
source. The transparent protector passes the processing laser
light, and suppresses dust, which is generated from the work
material irradiated with the processing laser light, entering into
the housing.
Advantageous Effect(s) of Invention
[0012] The transparent protector having the contaminants (dust) is
heated by the irradiated processing laser light. In the laser
processing head and laser processing system related to one aspect
of the present disclosure, the degree of the contaminants adhering
to the transparent protector can be detected by using the
temperature of the transparent protector. In other words, by using
the laser processing head and laser processing system related to
one aspect of the present disclosure, the degree of the
contaminants adhering to the transparent protector can be detected
in a method different from the conventional method.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a block diagram showing a schematic configuration
of a laser processing system in accordance with a first exemplary
embodiment.
[0014] FIG. 2 is a schematic diagram showing a configuration of a
laser processing head in accordance with the first exemplary
embodiment.
[0015] FIG. 3 is a plan view showing a transparent protector in
accordance with the first exemplary embodiment.
DESCRIPTION OF EMBODIMENTS
[0016] First, a schematic configuration of laser processing system
1 related to one aspect of the present disclosure is described.
Laser processing system 1 related to one aspect of the present
disclosure includes processing laser light source (simply referred
to also as "laser light source") 14; housing 30; transparent
protector 40 that is detachably fixed to housing 30; temperature
sensor 70 that detects the temperature of transparent protector 40;
and controller 12 connected to processing laser light source 14 and
temperature sensor 70. Housing 30 includes an optical path of
processing laser light (simply referred to also as "laser light")
LB from the processing laser light source 14. Transparent protector
40 passes processing laser light LB, and suppresses dust, which is
generated from work material W irradiated with processing laser
light LB, entering into housing 30. For example, when the
temperature of transparent protector 40 detected by temperature
sensor 70 exceeds an allowable temperature, controller 12 can
determine that the temperature of transparent protector 40 exceeds
the allowable temperature (or the allowable dirt degree of glass
plate 50). Therefore, controller 12 can urge a user to perform the
replacement of transparent protector 40.
[0017] Processing laser light LB is near-infrared light.
Transparent protector 40 has glass plate 50 having a portion for
passing processing laser light LB. Temperature sensor 70 may
include an infrared radiation thermometer. The thermometer
optically detects the temperature of glass plate 50 by detecting
the peak wavelength of far-infrared light generated by black-body
radiation from the dust adhering to glass plate 50. Even when
processing laser light LB is reflected on work material W adhering
to glass plate 50, temperature sensor 70 can clearly distinguish
between the reflected light (near-infrared light) and the
far-infrared light (black-body radiation light) to be detected.
Therefore, controller 12 can further certainly detect the degree of
the contaminants adhering to transparent protector 40 at a higher
reliability. In other words, controller 12 can accurately detect
that the temperature of transparent protector 40 exceeds an
allowable temperature, (or an allowable dirt degree of glass plate
50), furthermore the time for replacement of transparent protector
40.
[0018] Furthermore, glass plate 50 may include: exposure region 52
for passing processing laser light LB; and non-exposure region 54
that does not pass processing laser light LB. Temperature sensor 70
may optically detect the temperature of glass plate 50 in
non-exposure region 54. Even when processing laser light LB is
radiated to the dust adhering to glass plate 50, and a part of
glass plate 50 is heated locally the temperature of glass plate 50
in non-exposure region 54 that is apt to have a further uniform
temperature can be optically detected. Thus, the detection error of
the temperature due to variation (non-uniformity) of the dust
adhering to glass plate 50 can be suppressed as much as
possible.
[0019] Housing 30 may include shade 72 that blocks the light coming
into temperature sensor 70 from glass plate 50 in exposure region
52. Thus, the components of temperature sensor 70 can be protected
from the reflected light of processing laser light LB of a high
power, and the long-term reliability of temperature sensor 70 can
be secured.
[0020] Transparent protector 40 includes: glass plate 50 including
a portion for passing processing laser light LB; and frame 60 for
holding glass plate 50. The temperature sensor may detect the
temperature of glass plate 50 by electrically detecting the
temperature of frame 60. Similarly to temperature sensor 70 for
optically detecting the temperature of transparent protector 40,
--on the basis of the temperature of transparent protector 40 that
is indirectly detected by electrically detecting the temperature of
frame 60--, controller 12 can determine the dirt degree and/or the
time for replacement of transparent protector 40.
[0021] Furthermore, laser processing system 1 further includes a
display connected to controller 12. Controller 12 may cause the
display to display the temperature of transparent protector 40
detected by temperature sensor 70. Alternatively, controller 12 may
cause the display to display the output reduction rate representing
the output reduction of processing laser light LB radiated to work
material W. Here, the output reduction is caused by the dust
adhering to transparent protector 40. Thus, the user can know the
relative value (output reduction rate indicating the degree of
decrease in output) between the following values: the intensity of
processing laser light LB absorbed by the dust adhering to glass
plate 50; and the output intensity of processing laser light
LB.
[0022] Furthermore, laser processing system 1 further includes an
input unit connected to controller 12. Controller 12 may receive,
via the input unit, a set value of the output reduction rate
representing the output reduction of processing laser light LB
radiated to work material W. Here, the output reduction is caused
by the dust adhering to transparent protector 40. Thus, the user
can be informed of the time for replacement of transparent
protector 40 according to the cost-effectiveness demanded by the
user. Here, the time for replacement is obtained, by comparing the
detected output reduction rate of processing laser light LB
radiated to work material W with the set value of a previously set
output reduction rate.
First Exemplary Embodiment
[0023] Hereinafter, the exemplary embodiments of a laser processing
head related to the present disclosure and a laser processing
system using this are described with reference to the accompanying
drawings. In the description of the exemplary embodiments, the
terms (for example, "longitudinal" and "lateral") showing the
directions are appropriately used for facilitating the
understanding. These terms are used for description, and do not
limit the present disclosure. In each drawing, these sizes are
relatively shown in order to clarify the shapes or features of the
components of the laser processing head, and they are not
necessarily shown in the same scale ratio.
[0024] Laser processing system 1 related to the first exemplary
embodiment is described with reference to FIG. 1 to FIG. 3. FIG. 1
is a block diagram showing a schematic configuration of laser
processing system 1 in accordance with the first exemplary
embodiment. Laser processing system 1 schematically includes: laser
oscillation device 10; and laser processing head 20 connected to
laser oscillation device 10 via a process fiber (not shown). Laser
oscillation device 10 includes: controller 12; laser light source
14 electrically connected to controller 12; and display input unit
16 (user interface device). Laser processing head 20 includes
temperature sensor 70 described later in detail, and electrically
connected to controller 12 of laser oscillation device 10.
[0025] Laser light source 14 radiates laser light (processing laser
light) LB to work material (work) W, and welds, fuses, and punches
work material W. Hereinafter, as one example, laser light source 14
is a direct diode laser (DDL) light source for outputting laser
light LB of a high power (1 kW or more). The laser light LB from
laser light source 14 is near-infrared light as one example, and
its peak wavelength is 975 nm (0.975 .mu.m).
[0026] Infrared light is categorized into three regions according
to the wavelength, and is typically categorized into near-infrared
light (0.78 .mu.m to 2 .mu.m), mid-infrared light (2 .mu.m to 4
.mu.m), and far-infrared light (4 .mu.m to 1000 .mu.m). The
wavelength regions of these laser lights may be used as the
wavelengths of laser light LB. Temperature sensor 70 described
later may be an infrared radiation thermometer for optically
detecting the temperature by detecting infrared light within a
detection wavelength region. The wavelength region of laser light
LB coming from laser light source 14 is preferably different from
the detection wavelength region of temperature sensor 70.
[0027] Display input unit 16 includes: an inputting means (input
unit) allowing the user to adjust the intensity of laser light LB
coming from laser light source 14; and a displaying means (display)
for showing the temperature data from temperature sensor 70 to the
user. For example, display input unit 16 is a general-purpose touch
panel. Display input unit 16 related to one aspect of the present
disclosure is not limited to the general-purpose touch panel.
Display input unit 16 may be any user interface device. In the user
interface device, the user inputs an intensity into the user
interface device in order to adjust the intensity of laser light
LB, and the user is informed of the temperature data from
temperature sensor 70. The display input unit may separately
include the display and the input unit (for example, keyboard).
[0028] FIG. 2 is a schematic diagram showing a configuration of
laser processing head 20 in accordance with the first exemplary
embodiment. Laser processing head 20 is connected to an incident
connector (not shown) of the process fiber (not shown) for
transmitting laser light LB coming from laser light source 14.
Laser processing head 20 includes housing 30 having; incident end
32 for receiving laser light LB; and outgoing end 34 for outputting
(radiating) laser light LB. In other words, housing 30 includes the
optical path of laser light LB from laser light source 14 between
incident end 32 and outgoing end 34.
[0029] In housing 30, laser processing head 20 includes collimator
lens 36, collecting lens 38, and transparent protector 40.
Collimator lens 36 converts laser light LB coming from incident end
32 into parallel light. Collecting lens 38 collects the parallel
light Transparent protector 40 suppresses dust, which is generated
from work material W irradiated with the laser light LB, entering
into housing 30. In other words, transparent protector 40 protects
the components (especially, collecting lens 38) in housing 30 from
the dust of work material W.
[0030] Furthermore, housing 30 of laser processing head 20, which
is not shown in detail, has a (detachably fixable) slit into which
transparent protector 40 can be detachably fitted. As discussed
above, transparent protector 40 protects the components in housing
30 from the dust of work material W. Therefore, it is preferable
that transparent protector 40 has a shape and size so as to prevent
a gap from being formed between transparent protector 40 and
housing 30 when transparent protector 40 is fitted into the
slit.
[0031] FIG. 3 is a plan view showing transparent protector 40 in
accordance with the first exemplary embodiment. Transparent
protector 40 includes: glass plate 50 made of quartz glass or the
like; and frame 60 for fixing the periphery of glass plate 50.
Frame 60 may be made of any material having a heat resistance, but
it is preferable that this material is a metal (steel such as SUS)
having a high strength and an electric conductivity. Transparent
protector 40 is inserted into the slit of housing 30 in the
direction shown by arrow A. For convenience of description, in FIG.
3, frame 60 includes front end 62, rear end 64, right side portion
66, and left side portion 68. Glass plate 50 includes: exposure
region 52 for passing processing laser light LB; and non-exposure
region 54 that does not pass processing laser light LB.
[0032] Laser light source 14 provides laser light LB of a high
power such as, for example, 1 kW or more to process work material
W. Work material W irradiated with laser light LB of a high power
generates evaporated composition or dust (for example, zinc vapor)
of work material W. The evaporated composition or dust adheres to
transparent protector 40 attached to housing 30 of laser processing
head 20. The dust adhering to transparent protector 40 is opaque.
The dust adhering to exposure region 52 absorbs laser light LB
coming from laser light source 14. As a result, transparent
protector 40 in exposure region 52 is heated, and the intensity of
laser light LB radiated to work material W is reduced.
[0033] For example, when laser light LB of an intensity
corresponding to 1000 W is output from laser light source 14, and
when the dust of work material W absorbs laser light LB of the
intensity corresponding to 100 W, laser light LB of the intensity
corresponding to 900 W is radiated to work material W (output
reduction rate becomes 10%). Therefore, a desired processing rate
or processing accuracy cannot be obtained. Furthermore, transparent
protector 40 is extremely degraded, and the components in housing
30 are exposed to a high temperature of an allowable temperature or
more.
[0034] Incidentally, when the mass of glass plate 50 is about 5 g
and its specific heat is about 0.67 J/gK, the heat capacity
required for increasing the temperature of glass plate 50 by 1 K is
about 3.35 J. Glass plate 50 is heated to about 50.degree. C. (room
temperature is 20.degree. C.), when the following assumptions are
established: laser light LB corresponding to 100 W (10% of the
initial laser output intensity) is absorbed by the dust of work
material W; and only glass plate 50 of transparent protector 40 is
heated.
[0035] Laser processing head 20 in accordance with the first
exemplary embodiment includes temperature sensor 70 attached to
housing 30 as shown in FIG. 2. Laser light LB from laser light
source 14 is partially absorbed by the dust adhering to transparent
protector 40. The absorbed laser light LB is not radiated to work
material W. Temperature sensor 70 detects the intensity (or output
reduction rate of laser light LB) of the absorbed laser light
LB.
[0036] Next, temperature sensor 70 in accordance with the first
exemplary embodiment is described in detail. Temperature sensor 70
is an infrared radiation thermometer. The thermometer optically
detects the temperature of glass plate 50by detecting the
far-infrared light (peak wavelength) generated by black-body
radiation from the dust adhering to glass plate 50 of transparent
protector 40. Temperature sensor 70 (infrared radiation
thermometer), which is not shown in detail, may include the
following components, for example:
any photodetector (photodetector, photodiode, or photo-multiplier)
for converting light into electricity; and a bandpass filter for
passing the light of a specific wavelength band. Furthermore,
temperature sensor 70 may be a thermography that optically measures
the temperature of glass plate 50 and displays the measured
temperature as a color image.
[0037] Hereinafter, temperature sensor 70 is described as one
example.
[0038] Temperature sensor 70 includes a photodetector (PD).
Temperature sensor 70 receives the far-infrared light generated by
black-body radiation from the dust via a bandp as-filter for
passing light of a wavelength band of 8.83 .mu.m to 9.11 .mu.m, for
example. In other words, temperature sensor 70 outputs an electric
signal corresponding to the intensity of the light of a wavelength
band of 8.83 .mu.m to 9.11 .mu.m having passed through the bandpass
filter.
[0039] When the dust of work material W is not adhering to glass
plate 50 of transparent protector 40, most of laser light LB
transmits (passes) through glass plate 50, and is radiated to work
material W. Therefore, the temperature of glass plate 50 is
equivalent to room temperature (for example, 20.degree. C.).
However, when laser light LB is continued to be radiated to work
material W, the dust of work material W is accumulated on the glass
plate 50 of transparent protector 40. The dust is accumulated in a
larger area of glass plate 50 (the dirt gets worse), the loss of
laser light LB passing through glass plate 50 increases and the
temperature of glass plate 50 increases.
[0040] While, according to Wien's displacement law, peak wavelength
(.lamda.) of far-infrared light generated by black-body radiation
is expressed by the following equation using absolute temperature
(T). Here, the Wien's displacement law shows that the peak
wavelength of the black-body radiation (radiation from the
black-body) is inversely proportional to the temperature.
.lamda.=2897/T (1)
Here, the unit of peak wavelength (.lamda.) is micron (.mu.m), and
the unit of absolute temperature T is Kelvin (K).
[0041] Temperature sensor 70 has the characteristic in which the
electric signal output from temperature sensor 70 extremely
increases in the following cases: the far-infrared light generated
by black-body radiation from the dust of work material W has a peak
wavelength at which the intensity of the light becomes maximum in
the wavelength band of about 8.83 .mu.m to about 9.11 .mu.m; namely
the temperature of glass plate 50 is about 45.degree. C. to about
55.degree. C. (room temperature is 20.degree. C. (293K)). In other
words, when new transparent protector 40 is mounted to laser
processing head 20 and then laser light LB is radiated to work
material W; adhesion degree (contamination degree) of the dust to
glass plate 50 increases, and the electric signal output from
temperature sensor 70 to controller 12 increases.
Therefore, when the peak wavelength becomes lower than a
predetermined value and temperature sensor 70 detects the peak
wavelength of the wavelength band of about 8.83 .mu.m to about 9.11
.mu.m; controller 12 can determine that the temperature of glass
plate 50 arrives at about 45.degree. C. to about 55.degree. C.
Then, controller 12 cause display input unit 16 to display the
temperature (about 45.degree. C. to about 55.degree. C.) of glass
plate 50.
[0042] The wavelength band for passing the light of a bandpass
filter--which is not limited to the above-mentioned one --, may be
a wavelength band corresponding to the temperature of about
50.degree. C..+-.0.5.degree. C. of glass plate 50, for example. At
this time, controller 12 can more finely (more accurately) detect
the temperature range of the temperature increase of glass plate
50. Temperature sensor 70 includes a bandpass filter of a
wavelength band corresponding to each of a plurality of
temperatures to be detected. Controller 12 may more elaborately
monitor the temporal change of the temperature of glass plate 50
after the radiation of laser light LB. Thus, controller 12 may
show, to the user, the temperature of glass plate 50 as needed via
display input unit 16. Controller 12 may also show, to the user,
the dirt degree of glass plate 50, and the time for replacement of
transparent protector 40 or the sign of the time for
replacement.
[0043] Furthermore, when temperature sensor 70 has detected a peak
wavelength lower than the peak wavelength of the wavelength band of
about 8.83 .mu.m to about 9.11 .mu.m for example, as a
predetermined value: controller 12 can determine that glass plate
50 of transparent protector 40 absorbs laser light LB of an
intensity exceeding 10% of initial laser light LB, for example,
(output reduction rate exceeds 10%). Then, controller 12 causes
display input unit 16 to display this output reduction rate (for
example, 10%, or exceeding 10%). At this time, controller 12 may
inform, via display input unit 16, the user of the requirement of
replacement of transparent protector 40 or the approach to the time
for replacement.
[0044] Furthermore, the following method is allowed. The user
inputs, as a set value, the relative value (output reduction rate,
for example 10%) between the following values: the intensity of
laser light LB absorbed by the dust adhering to glass plate 50; and
the output intensity of laser light LB. When the relative value
arrives at the input output reduction rate, controller 12 may
inform the user of the arrival via display input unit 16. Thus, by
comparing the detected output reduction rate of processing laser
light LB radiated to work material W with the set value of a
previously set output reduction rate; the user is informed of the
time for replacement of transparent protector 40 according to the
cost-effectiveness demanded by the user. Here, when the user can
input any output reduction rate, a bandpass filter of a wavelength
band corresponding to each output reduction rate must be disposed
in temperature sensor 70.
[0045] In the above-mentioned example, display input unit 16
visually shows the time for replacement to the user, but is not
limited to this. The time for replacement may be shown to the user
using an acoustic means such as a buzzer.
[0046] As discussed above, laser light LB from laser light source
14 is near-infrared light having a peak wavelength of 975 nm (0.975
.mu.m), for one example. While, the black-body radiation light
coming from the dust adhering to glass plate 50 is far-infrared
light having a wavelength band of about 8.83 .mu.m to about 9.11
.mu.m, for example. In Patent Literature 1, the wavelengths of the
detected reflected light and the disturbance light (both are
near-infrared light) are the same, so that detection error is apt
to be caused. However, in the present disclosure, even when laser
light LB is reflected on work material W adhering to glass plate
50, the reflected light (near-infrared light) can be clearly
distinguished from far-infrared light (black-body radiation light)
to be detected. Therefore, the temperature of transparent protector
40, namely, the dirt degree of glass plate 50 (further, the time
for replacement of transparent protector 40) can be accurately
detected.
[0047] Furthermore, the dust of work material W does not always
uniformly adhere to glass plate 50, but adheres to a part of glass
plate 50. Therefore, a part of exposure region 52 of glass plate 50
is sometimes heated by laser light LB of a high power, and glass
plate 50 locally has high temperature. Furthermore, glass plate 50
has a low thermal conductivity and exposure region 52 is connected
to non-exposure region 54 in glass plate 50. Therefore, the heat
generated in exposure region 52 is conducted to non-exposure region
54, and glass plate 50 in non-exposure region 54 is apt to have
more uniform temperature. Therefore, preferably, temperature sensor
70 is configured to optically detect the temperature of glass plate
50 in non-exposure region 54. Specifically, temperature sensor 70
may be disposed so that the optical axis of the far-infrared light
coming into temperature sensor 70 points to non-exposure region 54.
Thus, the detection error of the temperature due to variation
(non-uniformity) of the dust adhering to glass plate 50 can be
suppressed as much as possible.
[0048] Incidentally, as discussed above, temperature sensor 70
(infrared radiation thermometer) related to the present disclosure
does not detect the reflected light by the dust adhering to glass
plate 50. However, the intensity (optical energy) of the reflected
light of laser light LB of a high power is extremely higher than
that of the far-infrared light (black-body radiation light).
Therefore, when the bandpass filter constituting temperature sensor
70 is exposed to the reflected light having a high optical energy
for a long time, the bandpass filter is heated to be deteriorated
and can damage the desired optical characteristic. Then, as shown
in FIG. 2, laser processing head 20 of the present disclosure may
include shade 72, which extends from the inner wall of housing 30,
between temperature sensor 70 and exposure region 52 of glass plate
50. Here, shade 72 is used for blocking the direct reflected light
of laser light LB coming into temperature sensor 70 from glass
plate 50 in exposure region 52. Thus, the components of temperature
sensor 70 are protected from the reflected light of laser light LB
of a high power, and the long-term reliability of temperature
sensor 70 can be secured.
Modified Example of First Exemplary Embodiment
[0049] Temperature sensor 70 in accordance with the first exemplary
embodiment has been described as an infrared radiation thermometer.
The thermometer optically detects the temperature of glass plate
50by detecting the far-infrared light (peak wavelength) generated
by black-body radiation from the dust adhering to glass plate 50 of
transparent protector 40. However, the temperature sensor of the
present disclosure may electrically detect the temperature of glass
plate 50.
[0050] Generally, when laser light LB is radiated to the dust
adhering to glass plate 50, glass plate 50 is heated, further the
heat is conducted to frame 60 for fixing the periphery of glass
plate 50, and frame 60 is indirectly heated. Therefore, by
detecting the temperature of frame 60, the temperature of glass
plate 50 can be indirectly detected.
[0051] The temperature sensor related to the modified example may
be a thermistor or thermocouple disposed at front end 62 or rear
end 64 of frame 60, for example. Alternatively, the temperature
sensor related to the modified example may detect the temperature
of frame 60, by detecting the electric resistance between the
terminals connected to right side portion 66 and left side portion
68 of frame 60 having an electric conductivity. Thus, similarly to
the first exemplary embodiment, controller 12 can determine the
dirt degree of glass plate 50 and the time for replacement of
transparent protector 40--on the basis of the indirectly detected
temperature of glass plate 50.
Other Example
[0052] In the description of the first exemplary embodiment and the
modified example, laser light source 14 is a direct diode laser
(DDL) light source, laser light LB from laser light source 14 is
near-infrared light, and its peak wavelength is 975 nm. However,
laser light source 14 is not limited to this. In other words, laser
light source 14 may radiate the light of another wavelength of the
DDL light source, or may be a light source other than the DDL light
source. Laser light LB from laser light source 14 may be the light
of a wavelength capable of being clearly distinguished from the
far-infrared light generated by black-body radiation from the dust
adhering to glass plate 50 of transparent protector 40. In other
words, it is preferable--in order to prevent a detection
error--that the wavelength region of the laser light LB from laser
light source 14 is different from the detection wavelength of the
infrared light used for optically detecting the temperature with
temperature sensor 70.
INDUSTRIAL APPLICABILITY
[0053] The present disclosure can be applied to a laser processing
head for detecting the degree of the contaminants adhering to a
transparent protector (glass plate) at a higher reliability.
REFERENCE MARKS IN THE DRAWINGS
[0054] 1 laser processing system [0055] 10 laser oscillation device
[0056] 12 controller [0057] 14 laser light source (processing laser
light source) [0058] 16 display input unit (user interface device)
[0059] 20 laser processing head [0060] 30 housing [0061] 32
incident end [0062] 34 outgoing end [0063] 36 collimator lens
[0064] 38 collecting lens [0065] 40 transparent protector [0066] 50
glass plate [0067] 52 exposure region [0068] 54 non-exposure region
[0069] 60 frame [0070] 62 front end [0071] 64 rear end [0072] 66
right side portion [0073] 68 left side portion [0074] 70
temperature sensor [0075] 72 shade [0076] W work material (work)
[0077] LB laser light (processing laser light)
* * * * *